There is known a variable inertia flywheel being allowed to change a moment of inertia, as a flywheel which is attached to an output shaft of an internal combustion engine. For example, there is known a flywheel apparatus having a wheel and an inertia ring which is provided near the wheel, the wheel and the inertia ring being connected by magnetic force which is generated when a current is supplied to an electromagnetic coil (see Patent Literature 1).